Conventionally, the Group III nitride semiconductor is utilized as function material for constituting a Group III nitride semiconductor light-emitting device of pn hetero junction structure, such as a light-emitting diode (LED), which radiates visible light of short wavelength (see JP-A 2000-332364). For example, when an LED which emits light in a near-ultraviolet region, blue region or green region is to be formed, n-type or p-type aluminum nitride gallium (AlXGaYN: O≦X, Y≦1, X+Y=1) is utilized for forming a clad layer (see JP-A 2003-229645). The gallium nitride indium (GaYInZN: O≦Y, Z≦1, Y+Z=1) is utilized for forming an active layer (light emitting layer) (see JP-B SHO 55-3834).
Conventionally, there is disclosed a technique for forming a light-emitting layer from single GaYInZN (O≦Y, Z≦1, Y+Z=1) (see JP-B SHO 55-3834). An example for forming a light-emitting layer from a super lattice structure called quantum well structure is also known (see JP-A 2001-102629). The quantum well structure is a structure in which barrier layers and well layers are alternately stacked periodically (see JP-A 2000-133883). For example, there is disclosed an embodiment in which a Ga0.7In0.3N layer is used as the well layer, and gallium nitride (GaN) is used as the barrier layer, and a light-emitting layer of a multiple quantum well structure is formed (see in JP-A 2001-102629).
However, in the above conventional techniques, the one end and the other end of the light-emitting layer are not limited to the barrier layers, and when one of the ends is a well layer, a carrier (electron) is prone to be dispersed toward the clad layer through the well layer, and there is a problem that the light emitting output is reduced by the same amount.
Even if the other end of the light-emitting layer that is in contact with the p-type clad layer is formed with the barrier layer, the thickness of the barrier layer is not enough, carrier charged from the n-type clad layer is not prevented from flowing toward the p-type clad layer, and there is a problem that the light emitting output is reduced by this influence.